YJ 2.5 Committed Suicide swaping w/ XJ 4.0 HO HELP - JeepForum.com
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Unread 12-02-2014, 09:35 PM   #1
weston579
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YJ 2.5 Committed Suicide swaping w/ XJ 4.0 HO HELP

I have a 90 YJ with a dead 2.5 and I picked up a 90 XJ donor w/ 4.0HO and an AX15 for cheap because it was wrecked in the front end. Im going to do the swap just happen to have a few questions. I have researched this topic for about 2 months and still have the same questions. Thanks in advanced for your input.

*Swap the XJ input (21 for 23) shaft and use my tcase because it's in line

*Can I use the motor & trans mounts from XJ because I know mine won't work

*Can I use a stock drive shaft front and rear if so out of what XJ,TJ or YJ with 4.0?

*Would it be easier to buy new gauges vs wiring my YJ s into the XJ wiring i know there different

*Can I use the trans cross member from the XJ for the ax15?

*Can I use the XJ radiator?

*I know there will be an issue with fuel pressure, what's the easiest way to get around that?

*Any other parts worth keeping axels, gears?

*Anything that I may not have thought about?

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Unread 12-03-2014, 08:09 AM   #2
Mike Romain
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Just a heads up for you. Check the crankshaft pulley for any in/out play or pull the pan and look at the thrust bearing. On the last couple Jeep engines I saw that were in front end collisions, that bearing was blown from the impact. On one, just draining the oil had pieces coming out.
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Unread 12-03-2014, 08:28 AM   #3
Jeepsr4me
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*Swap the XJ input (21 for 23) shaft and use my tcase because it's in line
Yes you can do that, but if the other(ax15) came with a Tcase use it
*Can I use the motor & trans mounts from XJ because I know mine won't work
yes just have to move your frame mounts
*Can I use a stock drive shaft front and rear if so out of what XJ,TJ or YJ with 4.0?
has to be the same set up jeep and YJ
*Would it be easier to buy new gauges vs wiring my YJ s into the XJ wiring i know there different
Just swap your sensors to the new engine and they will work. The Tach will need to be messed with
*Can I use the trans cross member from the XJ for the ax15?
no, since the jeep wrangler needs the skid, might as well use it too. and it has slots already in it for the trans mount
Can I use the XJ radiator?
*use the wrangler one.
*I know there will be an issue with fuel pressure, what's the easiest way to get around that?
use one from a cherokee. I like to go to You pull it yard and snake one since most tanks are setting in the back, I can get a pump in a few seconds.
*Any other parts worth keeping axels, gears?

*Anything that I may not have thought about?
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Unread 12-03-2014, 11:52 AM   #4
weston579
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The XJ was hit on the front left corner and only damaged the finder and bumper. Not a lot of damage overall.


*Swap the XJ input (21 for 23) shaft and use my tcase because it's in line
Yes you can do that, but if the other(ax15) came with a Tcase use it

I have read a few posts saying that the XJ Tcase is in at about a 15 degree angle and will hit the skid plate on the wrangler, thats why i was asking if anyone has run into this issue
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Unread 12-03-2014, 01:38 PM   #5
Jeepsr4me
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The Tcase is not the reason it is clocked lower. Its the tail end of the transmission. Not sure if its like that with 5 speed. But automatic is that way.
So use the tcase that is already with the trans. No need tearing it apart.

Getting driveshafts cut down is pretty cheap so dont worry about that.

edit 5 speeds might be... here is a pic that I think is a 5 speed being clocked drilled. I think that is a slave cyl hole on the left side so I am ASSUMING ......EASY TO DO dont sweat that either. I linked a way to do it also.
http://www.stu-offroad.com/engine/aw-4b/aw-4b-4.htm
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Unread 12-05-2014, 11:02 PM   #6
weston579
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Thanks the link was very helpful. 1 last question before I start the undertaking, should I stay with the stock gears in the YJ or gank the ones out of the XJ due to swapping trannys?
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Unread 12-06-2014, 06:14 AM   #7
fishadventure
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Quote:
Originally Posted by weston579
Thanks the link was very helpful. 1 last question before I start the undertaking, should I stay with the stock gears in the YJ or gank the ones out of the XJ due to swapping trannys?
It depends on your needs. Your heep has 4.11 gears and the XJ 'probably' has 3.08s. If you are mostly street and not off road the 3.08 gears can save you gas but the 4.11 will give you wicked pulling potential.

If it were me I would be torn on whether to switch to 3.08s - I have some XJ axles with 3.55 gears and I sometimes think I want them instead of the 4.11s in my project jeep which will be a six cylinder. It will probably be 90% road but the 3.55 gears sound like a nice compromise.
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Unread 12-11-2014, 01:48 PM   #8
TennesseeYJ
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Quote:
Originally Posted by Jeepsr4me View Post
The Tcase is not the reason it is clocked lower. Its the tail end of the transmission. Not sure if its like that with 5 speed. But automatic is that way.
So use the tcase that is already with the trans. No need tearing it apart.

Getting driveshafts cut down is pretty cheap so dont worry about that.

edit 5 speeds might be... here is a pic that I think is a 5 speed being clocked drilled. I think that is a slave cyl hole on the left side so I am ASSUMING ......EASY TO DO dont sweat that either. I linked a way to do it also.
The XJ 5-speed ax-15 are also clocked down. Easy fix though. Here is a drill template and How to video. The top video demo's the template
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